Autoxidisable coating composition

Abstract

An autoxidisable coating composition comprising i) 10 to 60 wt % of an autoxidisable material with: a) a number average molecular weight <4500 g/mol; b) optionally 1 to 20 carbohydrate units; c) a fatty acid content of ≧60 wt %; d) a viscosity at 100% solids in the range of from 0.05 to 5 Pa·s at 20+/−5° C. at a shear rate of 5000 s −1 ; ii) 90 to 40 wt % of an autoxidisable urethanised resin with: e) a number average molecular weight ≧4000 g/mol; f) a fatty acid content of ≧50 wt %; g) an acid value in the range of from 0 to 20 mgKOH/g resin; h) an isocyanate content in the range of from 1 to 35 wt % by weight of autoxidisable urethanised resin; where i)+ii)=100 wt %, based on the total solids content of the autoxidisable coating composition.

The invention claimed is: 
     
       1. An autoxidisable coating composition comprising:
 i) 10 to 60 wt % of an autoxidisable material having:
 a) a number average molecular weight <4500 g/mol; 
 b) optionally 1 to 20 carbohydrate units; 
 c) a fatty acid residue content of ≧60 wt %; and 
 d) a viscosity at 100% solids in the range of from 0.05 to 5 Pa·s at 20+/−5° C. at a shear rate of 5000 s −1 ; and 
 
 ii) 90 to 40 wt % of an autoxidisable urethanised resin which is a reaction product of at least an isocyanate, an alcohol, and an unsaturated oil or an unsaturated fatty acid, wherein the autoxidisable urethanised resin has:
 e) a number average molecular weight ≧4000 g/mol; 
 f) a fatty acid residue content of ≧50 wt %; 
 g) an acid value in the range of from 0 to 20 mgKOH/g resin; 
 h) an isocyanate content in the range of from 1 to 35 wt % by weight of autoxidisable urethanised resin; and 
 
 wherein i)+ii)=100 wt % based on total solids content of the autoxidisable coating composition. 
 
     
     
       2. An autoxidisable coating composition according to  claim 1  additionally comprising:
 iii) 0.5 to 40 wt % of a liquid medium; 
 wherein i)+ii)+iii)=100 wt % based on total amount of the autoxidisable coating composition. 
 
     
     
       3. An autoxidisable coating composition according to  claim 2 , wherein the composition has a volatile organic compound (VOC) level of 300 gl −1  or less at a viscosity ≦0.6 Pa·s at 20+/−5° C. and a shear rate of 5 000 s −1 . 
     
     
       4. An autoxidisable coating composition according to  claim 1  additionally comprising:
 iii) 41 to 50 wt % of a liquid medium; 
 wherein i)+ii)+iii)=100 wt %, based on total amount of the autoxidisable coating composition. 
 
     
     
       5. An autoxidisable coating composition according to  claim 4  , wherein the composition has a volatile organic compound (VOC) level of 500 gl −1  or less at a viscosity ≦0.2 Pa·s at 20+/−5° C. and a shear rate of 5 000 s −1 . 
     
     
       6. An autoxidisable coating composition according to  claim 1 , wherein the autoxidisable urethanised resin and/or the autoxidisable material have at least one air-drying group selected from the group consisting of fatty acid groups containing unsaturated bonds, (meth)allyl functional residues, -keto ester groups, -keto amide groups and combinations thereof. 
     
     
       7. An autoxidisable coating composition according to  claim 1 , wherein the composition is curable by autoxidation at ambient temperature. 
     
     
       8. An autoxidisable coating composition according to  claim 1 , wherein the autoxidisable material is selected from the group consisting of autoxidisable carbohydrate derivatives; fatty acid esters of glycerol; fatty acid esters of diglycerol; fatty acid esters of triglycerol; fatty acid esters of pentaerythritol; fatty acid esters of dipentaerythritol; fatty acid esters of tripentaerythritol; vegetable oils; and combinations thereof. 
     
     
       9. An autoxidisable coating composition according to  claim 1  wherein the autoxidisable material comprises 0 to 2 unreacted hydroxyl functional groups. 
     
     
       10. An autoxidisable coating composition according to  claim 1  wherein the autoxidisable urethanised resin is either:
 1) an autoxidisable urethanised alkyd which is a reaction product comprising at least:
 a) an isocyanate, 
 b) an alcohol, 
 c) an unsaturated oil and/or unsaturated fatty acid, and 
 d) a diacid; or 
 
 2) an autoxidisable urethanised oil which is a reaction product comprising at least:
 a) an isocyanate, 
 b) an alcohol, and 
 c) an unsaturated oil and/or unsaturated fatty acid. 
 
 
     
     
       11. An autoxidisable coating composition according to  claim 1 , wherein the autoxidisable urethanised resin comprises at least 5 to 35 wt % of an isocyanate, by weight on solid autoxidisable urethanised resin. 
     
     
       12. An autoxidisable coating composition according to  claim 1 , wherein the autoxidisable urethanised resin comprises a polymeric polyol of functionality ≧2 and a number average molecular weight Mn within the range of from 500 to 8,000 g/mol. 
     
     
       13. An autoxidisable coating composition according to  claim 2 , wherein the composition has a maximum of 300 gl −1  of volatile organic compounds at a pigment volume concentration (PVC) of ≦40 vol %. 
     
     
       14. An autoxidisable coating composition according to  claim 1 , wherein the autoxidisable urethanised resin is a reaction product comprised of:
 a) from 50 to 80 wt % of at least an unsaturated oil or unsaturated fatty acid; 
 b) from 1 to 20 wt % of a polymeric polyol; 
 c) from 0 to 30 wt % of a diacid; and 
 d) from 1 to 35 wt % of an isocyanate, 
 wherein a)+b)+c)+d)=100 wt %, based on the total solids content of the autoxidisable urethanised resin. 
 
     
     
       15. The autoxidisable coating composition according to  claim 8 , wherein the autoxidisable material is at least one autoxidisable carbohydrate derivative selected from the group consisting of sucrose soyate, sucrose safflowerate and sorbitol. 
     
     
       16. A paint composition comprising an autoxidisable coating composition according to  claim 1 , and at least a drier salt. 
     
     
       17. A method for coating a substrate comprising applying the autoxidisable coating composition according to  claim 1  onto a substrate, and then drying the applied coating composition. 
     
     
       18. A substrate coated with the autoxidisable coating composition according to  claim 1 . 
     
     
       19. An indoor or outdoor coating material which comprises the autoxidisable coating composition according to  claim 1 .